In current telecommunications networks, especially mobile communication networks, policy and/or charging control is applied to users of the telecommunications network. The policy and charging control functionality is provided by a policy and charging control (PCC) architecture and encompasses two main functions:                Event and Session Based Charging, including charging control and online credit control;        Policy control (e.g. gating control, Quality of Service (QoS) control, QoS signalling, etc.).        
The policy and charging control (PCC) functionality comprises the functions of the policy and charging enforcement function (PCEF), the bearer binding and event reporting function (BBERF), the policy and charging rules function (PCRF), the application function (AF), the traffic detection function (TDF), the online charging system (OCS), the offline charging system (OFCS) and the subscription profile repository (SPR) or the user data repository (UDR).
The policy and charging rules function (PCRF) encompasses policy control decision and flow based charging control functionalities. The PCRF provides network control regarding the service data flow detection, gating, QoS and flow based charging (except credit management) towards the policy and charging enforcement function (PCEF).
The policy and charging enforcement function (PCEF) encompasses service data flow detection, policy enforcement and flow based charging functionalities. This functional entity is usually located at the gateway entity (e.g. GGSN (Gateway GPRS Support Node) in the General Packet Radio Service (GPRS) case, and SGW (serving gateway) in the Long Term Evolution (LTE) or wireless local area network (WLAN) case). It provides service data flow detection, user plane traffic handling, triggering control plane session management (where the IP-CAN (IP connectivity access network) permits), QoS handling, and service data flow measurement as well as online and offline charging interactions. The online charging system (OCS) performs the service data flow based credit control function.